1. Field of the Invention
The invention relates to a memory module, one or more memory chips being applied to a printed circuit board and the printed circuit board being connected to an overall system.
2. Description of the Related Art
Novel memory modules usually have a printed circuit board to which memory chips are applied, the latter being connected, via rewiring lines on the printed circuit board, to a buffer chip which is likewise applied to the printed circuit board. In this case, the buffer chip is used to provide a very fast point-to-point connection to an external memory controller. That is to say, the buffer chip establishes a very fast serial data connection to an overall system. The buffer chip parallelizes data to be written to the memory chips and serializes the data to be read from the memory chips. This means that communication on the printed circuit board of the memory module takes place at a lower clock speed than communication between the memory module and the overall system.
Due to this operation, in particular due to the high transmission frequency of the buffer chips to the overall system, the buffer chip has very high power consumption. This high power consumption results in the buffer chip being severely heated during operation. The generation of heat in the buffer chip also affects, via the heat conduction of the printed circuit board, the memory chips applied to the printed circuit board since increased temperatures of the memory chips lead to increased leakage currents in the memory cells and the demands imposed on the data retention time of the memories are thus adversely affected.
Apart from various attempts at reducing the power consumption of the buffer chip, no measures for protecting the memory chips from increased evolution of heat in the buffer chip have hitherto been disclosed.